Code A Registered Office: Aakash Tower, 8, Pusa Road, New Delhi-110005. Ph.: (011) 47623456 Physics, Chemistry & Mathematics SAMPLE QUESTION PAPER FOR SOLUTIONS CBSE Class XII Board Exam 2018
CodeA
Registered Office: Aakash Tower, 8, Pusa Road, New Delhi-110005. Ph.: (011) 47623456
Physics, Chemistry&
Mathematics
SAMPLE QUESTION PAPER FOR
SOLUTIONS
CBSE Class XII Board Exam 2018
(1)
Physics (Code-A) Solutions of Sample Question Paper for Class XII
SECTION-A
1. radian
2. When one slit is closed, amplitude becomes half and hence intensity becomes one fourth, and there is no
interference.
3. ( ) Y A B A B AB
4. Biconcave lens will change its nature as refractive index of outside medium is greater than that of lens material,
so it will behave as converging lens.
5. (a) Mutual inductance increases on decreasing distance.
(b) Mutual inductance decreases on decreasing the number of turns.
SECTION-B
6. Following are the advantages of digital data over the analog data :
(i) Digital data are immune from imperfection of electronic system.
(ii) By coding the digital data we achieve secure transmission of data.
(iii) Digital data have better noise immunity.
(iv) Digital data can be processed by digital circuit component which are cheap and easily available.
OR
NAND-gate and NOR-gate are the universal gates. They are called universal gates because by using only
NAND-gates or NOR-gates, all the other three gates (OR, AND, NOT-gate) can be formed.
The below combination of NAND-gates works as a OR-gate.
A
B
Y
7. For I = 5 sin(314 t); I0 = 5 A
Iav
= 2 10
5 3.23.14
A
Irms
5 2
0.707 5 3.5352 2
Irms
= 3.535 A
8. KVL based on energy conservation principle while KCL is based upon charge conservation principle.
Physics (Theory) - Class XII (Code-A)
SOLUTIONS
(2)
Solutions of Sample Question Paper for Class XII Physics (Code-A)
9. (a) As, V = – Ir
V
I
As R increases, current (I), in the circuit decreases and terminal voltage (V) increases.
(b) The current across a cell is, I = R r
when R increases, I decreases.
I(A)
R( )
( / ) r
10. Electrons revolve around nucleus and the required centripetal force is provided by attractive force between
electron and nucleus.
2 2
2
kze mv
rr
2
2 kzemv
r
K.E. = 21
2mv =
2
2
kze
r
And potential energy,
U =
2kze
r
Total energy,
E = K.E. + U
E =
2
2
kze
r
SECTION-C
11. p–n junction is developed from a single crystal by introducing donor impurities on one side and acceptor into
the other side. The donor ion is represented by a plus (+) sign because this impurity atom donate an electron
hence it becomes a positive ion. The acceptor ion is indicated by a minus-sign because it accepts an electron
hence it becomes a negative ion.
(3)
Physics (Code-A) Solutions of Sample Question Paper for Class XII
Due to density difference across the junction, the holes diffuse toward n-side where the number of holes are
less. Similarly electron diffuse to p-side of the junction. This migration of electron and holes across junction
due to concentration difference is termed as diffusion. At the junction, combination of holes and electrons takes
place since the region of the junction is depleted of the migrating charges it is called the depletion region or
transition region. On the n-side of depletion layer electrons are lost, hence a positive charge build-up on this
side. Similarly the p-side of depletion layer develops a negative charge within depletion layer, there are no mobile
charge carrier. Charge density is positive toward n-side and negative toward p-side. This charge separation
across junction gives rise to an electric field. This electric field is directed from positive charge to negative
charge. Due to this field the positive end of depletion layer is at high potential and the negative end is at low
potential. This potential is called potential barrier or junction barrier which try to oppose any further diffusion
of charge carrier.
If the positive terminal of battery is attached to the p-side and negative terminal of battery toward the n-side,
the field due to this voltage difference compensates the barrier potential and charge carriers are forced to move
across the function. This is called forward bias.
On the other hand, if polarity of battery gets reversed then potential barrier further rises and there is very little
reverse current or practically no flow of current in the circuit.
OR
Vi
Inputvoltage
RB
VBB
I B
IC
VCC
IC
VBE I
E
E
npn
VCE
RC Output
voltage, V0
BC
n-p-n CETransistor in configuration
For Silicon Transistor :
For output circuit V0 = V
CC – I
CRC
…(i)
For input circuit Vi = I
BRB + V
BE…(ii)
(a) As long as, 0.7 Vi
V , there is no collector current.
Then, V0 = V
CC (from equation (i))
The transistor will be in cut-off state.
(b) When 0.7 V 1.0 Vi
V ,
With the increase of Vi beyond 0.7 V, I
C increases almost linearly and V
0 decreases linearly till V
i becomes
1.0 V.
In this situation, the transistor is in active state.
(c) When 1.0 Vi
V ,
The variation of Vi and V
0 is non-linear. In this situation the collector current I
C becomes maximum and the
transistor is in saturation state.
12. Space wave propagation : When the radio waves from the transmitting antenna reach the receiving antenna
either directly or after reflection from the ground or in troposphere, the wave propagation is called space wave
propagation.
(4)
Solutions of Sample Question Paper for Class XII Physics (Code-A)
The space wave communication is used in the following communication methods :
(i) For transmitting high frequency TV and FM signals
(ii) Microwaves link and satellite communication.
Let h1 and h
2 be the height of transmitting and receiving antenna respectively, then
1 2h h h
2 1h h h (Range of receiving antenna)
If R is radius of the Earth
12R Rh
trans.
22R Rh
receive =
12 ( )R h h
Total range of transmitting and receiving antenna
1 12 2 ( )R R R Rh R h h
total trans. receive
The range will be maximum; if
1
( ) 0d
Rdh
total
1 1
1
( 2 2 ( )) 0d
Rh R h hdh
⇒
½ ½
1 1
1
( ) 0d
h h hdh
⎡ ⎤⇒ ⎢ ⎥⎣ ⎦
1 1h h h⇒
12
hh⇒
13.
d
ue
A
v0
u0
A
B
A1
B
A
C2
C1
B
Objective
Eye-lens
Magnifying power, m
tan
tanm
2
2
C BA B
C B AB
[A1B = AB]
m = me × m
0
01
e
dm
f
⎛ ⎞ ⎜ ⎟⎝ ⎠
(5)
Physics (Code-A) Solutions of Sample Question Paper for Class XII
0
0
1
e
v d
u f
⎛ ⎞ ⎜ ⎟ ⎝ ⎠
0
0
1
e
v dm
fu
⎛ ⎞ ⎜ ⎟
⎝ ⎠
14. For a balanced metre bridge as shown in figure, 100
X l
Y l
, where l = AD = 60 cm
601.5
100 100 60
lX Y Y Y
l
⎡ ⎤ ⎡ ⎤ ⎢ ⎥ ⎢ ⎥ ⎣ ⎦ ⎣ ⎦
When 15 resistance is connected in series with Y.
Let Y be the resistance of the series combination of Y and 15 resistance and the balance point be at
a distance of l from end A.
Then Y = Y + 15; l = l – 10 = 60 – 10 = 50 cm
501.5 ( 15) 1.5 15
100 100 50
lX Y Y Y Y Y
l
⎡ ⎤ ⎡ ⎤ ⇒ ⇒ ⎢ ⎥ ⎢ ⎥ ⎣ ⎦ ⎣ ⎦
30Y
Also, 1.5 ; 30 1.5 30 45X Y Y X ⇒
when 30 resistance is connected in parallel with Y. Let Y be the resistance of the parallel combination of
Y and 30 resistance then 30 30 900
1530 30 60
Y
If balance point is at a distance of l from end A
100
lX Y
l
⎡ ⎤ ⎢ ⎥⎣ ⎦
45 15100
l
l
⎡ ⎤ ⎢ ⎥⎣ ⎦
3 (100 ) 4 300l l l ⇒ ⇒
75 cml ⇒
15. (a) (i) EM wave propagates in form of varying electric and magnetic fields such that two fields are
perpendicular to each other and also to the direction of propagation of the waves. In other words;
electromagnetic waves are transverse in nature.
(ii) EM waves are produced by accelerated charges.
(iii) In free space, EM wave travels with a velocity, 8 1
0 0
13 10 ms
C .
(iv) EM waves do not require any material medium for their propagation.
(b) (i) Microwaves
(ii) -rays
(iii) X-rays
(6)
Solutions of Sample Question Paper for Class XII Physics (Code-A)
16. Since 1
2
2R
R (Where R
1 and R
2 are resistances of upper and lower part)
1 2
2 1
1
2
I R
I R⇒
I2
I1
I I
22 ,I I⇒ and 1 2 1 2
2,
3 3
I II I I I I ⇒
Clearly field due to straight part at centre of circle is zero.
So B due to upper and lower arc
0 2 1
4
I IB
R R
⎡ ⎤ ⎢ ⎥ ⎣ ⎦
0 02 1 1
4 3 3 4 3
⎡ ⎤ ⎢ ⎥⎣ ⎦
I IB
R R, outwards to the plane of paper
17. Let the alternating voltage is E = E0cost.
Let current lags the voltage by angle ,
Where I0 =
0
2
2 1
E
R LC
⎛ ⎞ ⎜ ⎟⎝ ⎠
and
1
tan
LC
R
Average power = 0
T
EIdt
T
∫
= 0 0
0
1( cos ) ( cos( ))
T
E t I t dtT
∫
= 20 0
0
(cos ( )cos cos sin sin ) ∫T
E It t t dt
T
= 0 0
1cos
2E I
average rms rmscosP E I
18. Given, Voltage across RB = 10 V
Resistance RB = 400 k
VBE
= 0, VCE
= 0 RC = 3 k
IB =
Voltage acrossB
B
R
R
=6
3
1025 10 A 25 A
400 10
(7)
Physics (Code-A) Solutions of Sample Question Paper for Class XII
Voltage across RC = 10 V
IC = 3
Voltage across 10
3 10
C
C
R
R
= 3.33 × 10–3 A = 3.33 mA
3
6
3.33 10
25 10
C
B
I
I
= 1.33 × 102 133
19. Given, for the first condition, wavelength of light = 600 nm
and for the second condition, wavelength of light = 400 nm
Also, maximum kinetic energy for the second condition is equal to the twice of the kinetic energy in first
condition.
i.e.,max max
2K K
Here,max
hc
K
max 0
2hc
K
1240 12402 1240 eV nm
600 400
⎛ ⎞ ⎛ ⎞ ⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠∵ �hc
1240
1.03 eV1200
20. In case of AM, the instantaneous voltage of carrier waves is varied by the modulating wave voltage. So, during
the transmission, noise signals can also be added and receiver assumes noise a part of the modulating signal.
In case of FM, the frequency of carrier waves is changed as the change in the instantaneous voltage of
modulating waves. This can be done by mixing at transmitting end and not while the signal is propagating
through the channel. So noise does not effect FM signal.
21. (a) According to question, a nuclide 1 is said to be mirror isobar of nuclide 2, if Z1 = N
2, Z
2 = N
1.
Now in 11
Na23, Z1 = 11 and N
1 = 23 – 11 = 12
Mirror isobar of 11
Na23 is 12
Mg23, for which Z2 = 12 = N
1 and N
2 = 23 – 12 = 11
(b) As 23
12Mg contains even number of protons (12) against
23
11Nawhich has odd number protons (11), therefore
23
12Mg has greater binding energy than
11Na23.
22. An inductor opposes flow of current through it by developing a back emf according to Lenz’s law. The induced
voltage has a polarity so as to maintain the current at its present value. If the current is decreasing, the polarity
of the induced emf will be so as to increase the current and vice-versa.
(8)
Solutions of Sample Question Paper for Class XII Physics (Code-A)
Since, the induced emf is proportional to the rate of change of current, it will provide greater reactance to the
flow of current if the rate of change is faster, i.e., if the frequency is higher. The reactance of an inductor,
therefore, is proportional to the frequency. Mathematically, the reactance offered by the inductor is given by
XL = L.
SECTION-D
23. (a) 50 Hz, 220 V RMS.
(b) No
(c) Mutual Induction
SECTION-E
24. (a) 3 F
3 F 1 F 2 F
2 F
100 V
⇓ equivalent
2 F
3 F
3 F 2 F
1 F
100 V
C1 = 3 F + 3 F = 6 F, C
2 = 1 F + 2 F = 3 F
1 2
12
1 2
6 32
6 3
C CC
C C
F
Finally equivalent capacitor C12
= 2 F and 2 F are in parallel.
Net capacitance C1 = 2 F + 2 F = 4 F
q = CV = 4 × 10–6 × 100 = 4 × 10–4 C
Also, total energy stored
(9)
Physics (Code-A) Solutions of Sample Question Paper for Class XII
2 6 21 14 10 100 0.02 J
2 2U CV
q = charge = 4 × 10–4 C
U = 0.02 J
(b) The plate B is earthed
V = potential difference = E d =
0
d⎛ ⎞ ⎜ ⎟⎝ ⎠
Q –Q
BA
0
QV d
A
0AQ
CV d
⇒
OR
(a)
+ + + + + + + + + + + + + + + + + + + + + + +
E
l
Figure shows a small part of infinitely long cylindrical non conducting wire.
Using
0
.
inq
E dA ∫
�
�
0
0 cos0I
EA
0
(2 )l
E rl
⇒
02
Er
⇒
(b) Since electric flux has only x-component. (electric flux) through four faces (other than M and N)
= ExS cos /2 = 0
Ex = 5Ax + 2B
Magnitude of electric field at face M (x = 0)
EM
= 5 × 10 × 0 + 2 × 5 = 10 NC–1
at x = 0.1 m
EN = 5 × 10 × 0.1 + 2 × 5 = 15 NC–1
(10)
Solutions of Sample Question Paper for Class XII Physics (Code-A)
M through face M
M
= EM
.A cos = 10 × (0.1 × 0.1) × cos180°
= 0.10 NmC–1
N
= EN.A cos = 15 × 0.1 × 0.1 × cos0°
= 0.15 NmC–1
Net flux through cube
= N –
M = 0.15 – 0.10 = 0.05 NmC–1
From Gauss’s theorem,
0 q = 8.85 × 10–12 × 0.05
q = 0.443 × 10–12 C
25. The path difference between two rays coming from holes S1 and S
2 is (S
2P – S
1P).
X
x –
x +
d
2d
2
P
O
D
d
S1
S2
Now, (S2P)2 – (S
1P)2 =
2 2
2 2
2 2
d dD x D x
⎡ ⎤ ⎡ ⎤⎛ ⎞ ⎛ ⎞ ⎢ ⎥ ⎢ ⎥⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠⎣ ⎦ ⎣ ⎦= 2xd, where S
1S
2 = d and OP = x
(S2P + S
1P) (S
2P – S
1P) = 2xd
2 1
2 1
2xdS P S P
S P S P
If x, d << D, then negligible error will be introduced if (S2P + S
1P) in the denominator is replaced by 2D.
S2P – S
1P =
xd
D
For maximum, S2P – S
1P = n
Thus, xd
nD
Or, ,
n
n Dx x
d
n = 0, ±1, ±2, ±3, ... [For maxima]
Now, for minimum, S2P – S
1P = (2n – 1)
2
(11)
Physics (Code-A) Solutions of Sample Question Paper for Class XII
Thus (2 1)2
xdn
D
Or, (2 1)2
n
Dx x n
d, n = ±1, ±2, ±3, ... [For minima]
Thus, bright and dark bands appear on the screen. Such bands are called ‘fringes’. These dark and bright
fringes are equally (spaced).
Expression for fringe width ()
Let nth order bright fringe is at a distance xn an (n + 1)th order bright fringe is at x
n+1 from O. Then
1
( 1)and
n n
n D n Dx x
d d
Now the fringe width is
1n n
Dx x
d
Thus, the expression for fringe width is D
d
OR
(a) Let magnetic field due to current element Idy at P is given by
0
3
( ) sin(90 )
4
I dy rdB
r
0 0
2 2 2
cos cos
4 4 ( )
I dy I dy
r y d
We have,
tany
d
2secdy d d⇒
90° +
p
d
yr
I
dy
2
0
2 2
cos sec
4 sec
I d ddB
d
⇒
0 (cos )4
Id
d
0cos
4
IB dB d
d
⇒
∫ ∫
0 (sin sin )
4
I
d
(b) For infinite wire, 2
0sin sin
4 2 2
IB
d
⎛ ⎞⇒ ⎜ ⎟⎝ ⎠
0 2
4
I
d
(12)
Solutions of Sample Question Paper for Class XII Physics (Code-A)
For semi-infinite wire, 0,2
0sin0 sin
4 2
IB
d
⎛ ⎞ ⎜ ⎟⎝ ⎠
0
4
IB
d
⇒
26. (a) Device ‘X’ is a capacitor.
(b) Curve A shows power consumption over a full cycle, curve B shows voltage and curve C shows current.
As in a perfect capacitor the current leads the voltage by a plane angle of /2.
(c) Z = XC =
1
C
1
2C
C
Xf
XC
f1
CX
f
(d) Consider a capacitor with capacitance C be connected to an AC source with an emf having instantaneous
value.
C
E
E = E0sint ... (i)
Due to this emf, charge will be produced and it will charge the plates of capacitor with positive and negative
charge. If potential difference across the plates of capacitor is V, then
orq
V q CVC
The instantaneous value of current in the circuit
( )( )
dq d CEI V E
dt dt
0 0
( sin ) ( sin )d
CE t E E tdt
= 0cosCE t
= 0
cos [ cos sin( / 2 )]1/
C
Et t t
I = 0
sin( / 2)1/
C
Et
... (ii)
(13)
Physics (Code-A) Solutions of Sample Question Paper for Class XII
I will be maximum when sin(t + /2) = 1 so that I = I0
Where, peak value of current I0 =
0
1/C
E
I = I0 sin (t + /2) ... (iii)
From (i) and (iii) it is clear current leads the voltage by a phase angle of /2.
t
E Iand
E
I
ORAC generator
AxleCoil
SN
Sliprings Alternating emf
Carbonbrushes
Let, = t is the angle made by area vector of coil with magnetic field.
Magnetic flux linked with coil is given by,
= NBAcos = NBAcost
sind
NBA tdt
sind
NBA tdt
By Faraday’s law of EMI, e = d
dt
Induced emf is given by,
e= NBAsint
e= e0sint
Where, e0= NBA= peak value of induced emf
(14)
Solutions of Sample Question Paper for Class XII Physics (Code-A)
Induced
emf
0
O T/4 T/2 3 /4T
90° 180° 270° 360°Time
The mechanical energy spent in rotating the coil in magnetic field appears in electrical energy.
� � �
(15)
Chemistry (Code-A) Solutions of Sample Question Paper for Class XII
SECTION-A
1. When constituent particles are present only at the corner positions of an unit cell, it is called primitive unit
cell.
2. Foam
For example - Whipped cream
3. 2-Phenylethan-1-ol
4. K3[Al(ox)
3] or K
3[Al(C
2O
4)3]
5. CH — C — Br3
CH3
CH3
would give faster SN1 reaction than CH
3 – CH
2 – Br.
SECTION-B
6. Q = It = 0.5 × 2 × 60 × 60 = 3600 C
Electrons flowing through the wire on passing charge 1 F (96500 C) = 6.02 × 1023
Electrons flowing through the wire on passing 3600 C charge =
23226.02 10
3600 2.24 1096500
7. (i) C6H
5CH
2NH
2 > C
6H
5NHCH
3 > C
6H
5NH
2
(ii)
NH2
CH3
>
NH2
>
NH2
NO2
8. (i) COCl 6NH + AgNO3
3 3AgCl
(1 mol) (3 mol)
Structural formula of complex = [Co(NH3)6]Cl
3
(ii) Hexamminecobalt (III) chloride.
9. (i) Order of reaction = zero
(ii) Unit of k = mol L–1 sec–1
10. (i)
S OHO
OHTriangular pyramidal
(ii) Xe
O
Square pyramidalF
F
F
F
Chemistry (Theory) - Class XII (Code-A)
SOLUTIONS
(16)
Solutions of Sample Question Paper for Class XII Chemistry (Code-A)
OR
(i)
P
OHHO
OH
Tetrahedral
O
(ii)Xe
O
Triangular pyramidalOO
SECTION-C
11. d = 3
A
ZM
a N
7.5 = 10 3 23
2 M
(500 10 ) 6.02 10
M = 282 g/mol
Number of moles = 300
282
Number of atoms = 23300
6.02 10282
= 6.4 × 1023
12. (i) Red phosphorus is less reactive than white phosphorus as white phosphorus has greater angle strain in
P4 molecule.
(ii) Because halogens have high effective nuclear charge and smallest size in respective period.
(iii) In N2O
5, the oxidation state of N is +5 whereas in N
2O
3, it is +3.
Higher the oxidation state of central atom in nitrogen oxide, higher will be acidic character.
13.
2
s urea
H O
P° – P n
P° n
s23.8 P
23.8
=
2
2
urea H O
urea H O
W MW
MW W
s23.8 P
23.8
=
30 18
60 846
23.8 – Ps = 0.0106 × 23.8 = 0·253
Ps = 23.8 – 0.253 = 23.547 mm Hg
14. Ideal solution
(i) Obeys Raoult's law at every range of concentration.
(ii) Neither the heat is absorbed nor evolved.
Non-ideal solution
(i) They do not obey Raoult's law.
(ii) Heat is evolved or absorbed during dissolution.
(17)
Chemistry (Code-A) Solutions of Sample Question Paper for Class XII
15. A0 = 100%
A = (100 – 25)% = 75%
t = 20 min.
k = 0A1
2.303 logt A
k = 1 100
2.303 log20 75
= 0.0144 min–1
For 75% completion of reaction,
t = 0A1
2.303 logAk
t = 1 100
2.303 log0.0144 25
= 96.3 min
16. (a) These are sodium salt of sulphonated long chain alcohols or hydrocarbon e.g., :- Sodium dodecylbenzene
sulfonate.
(b) The antibiotics which kill or inhibit a short range of gram-positive or gram-negative bacteria are known as
“narrow spectrum antibiotics” but if they are effective against a single organism or disease, they are
referred to as “limited spectrum antibiotics”.
17. (a) Nylon-6, 6
NH2 – (CH
2)6 – NH
2COOH – (CH
2)4 – COOH
Hexamethylene diamine Adipic acid
(b) Melamine-formaldehyde polymer
NH N
2
NH2
NH2
N
Melamine
N
HCHO
Formaldehyde
(c) Buna-S
2 2
1.3 butadiene
CH CH CH CH
CH CH2
Styrene
OR
(a) Buna-N
CH = CH – CH = CH + CH = CH2 22
CH1, 3-Butadiene Acrylonitrile
(b) Natural rubber
CH = C – CH = CH2 2
CH3
2-methyl-1, 3-butadiene
(c) Teflon
CF2 = CF
2
Tetrafluoroethylene
(18)
Solutions of Sample Question Paper for Class XII Chemistry (Code-A)
18. (a) CH3COOH
NH /3
CHCl alc.KOHBr /KOH 323 2 3 2 3
A B C
CH CONH CH NH CH NC
(b) C6H
5N
2
+BF4
– NaNO /Cu2
NO2
(A)
Fe/HCl
NH2
(B)
CH COCl/Pyridine3
NHCOCH3
(C)
19. (i) CH – CH – C – CH3 2 3
Br
CH3
(ii) CH3 – CH
2 – CH = CH – CH
3
(iii)
CH3
CH3
CH3
CH3
+
20. (i) van-Arkel method.
Ni (impure) + 4CO
4
Volatile
Ni(CO) Ni (pure) + 4CO
(ii) (a) To decrease the melting point of mixture.
(b) To increase electrical conductivity of Al2O3.
(iii) Limestone (CaCO3) acts as flux in the extraction of iron from its oxides.
CaCO3
CaO + CO2
2 3(Impurity) (Slag)
CaO + SiO CaSiO
21. (i) CH – C – I + CH OH3 3
CH3
CH3
(ii) CH – CH – C – CH3 2 3
O
(iii)
CHO
OH
22. (i) (CHOH)4
(CHOH)4
CHO CH = N – OH
CH OH2
CH OH2
NH OH2
(ii) In neutral amino acid, –COOH loses a proton and –NH2 of same molecule accept a proton. Due to this
reason, amino acids are amphoteric in nature.
(iii) Because vitamin C is water soluble and it is readily excreted in urine.
(19)
Chemistry (Code-A) Solutions of Sample Question Paper for Class XII
23. (i) Caring and true friendship.
(ii) Drugs that are used to neutralize acidity in stomach are called antacids. For example, NaHCO3 and
Mg(OH)2.
(iii) No, because excessive HCO–
3 can make the stomach alkaline and trigger the production of even
more acid.
SECTION-D
24. (i) (a) Due to lanthanoids contraction.
(b) In case of transition element ns and (n – 1)d electron both participate in bonding due to less
energy difference when ns electron take place in bonding they exhibit lower oxidation state while
in case of higher o.s. both orbital electrons involve in bonding.
(ii) (a) 2 KMnO4 K2MnO4 + MnO2 + O2
(b) 2 Na2CrO4 + 2H+ Na2Cr2O7 + 2Na
+ + H2O
OR
(i) (a) Stability of ions in aqueous state depends on electrode potential because due to small size Cr+3
is more stable.
(b) Mn+3
is strong oxidising agent as Mn+2
is more stable than Mn+3
due to its half filled
configuration.
(c) Ti+4
is colourless ion due to d0 configuration of ion.
(ii) Similarity :
* Both series element exhibit mainly +3 oxidation state.
Difference :
Lanthanoids have less tendency of complex formation whereas actinoids have high tendency of
complex formation.
25. E°cell = 0.34 + 2.37 = 2.71
2
cell cell2
Mg0.06E E log
n Cu
⎡ ⎤⎣ ⎦
= 0.06
2.71 log102
= 2.68 V
G = –nFEcell = –2 × 96500 × 2.68 = –5.17 × 105 J
OR
(XCl) = (X+) + (Cl
–)
= 73.5 + 76.5
= 150
2
1000 1000 2.48 10XCl 124
M 0.2
0
XCl 1240.83
150XCl
(20)
Solutions of Sample Question Paper for Class XII Chemistry (Code-A)
26. (a) (i) A is CH3CHO
B is CH3CH = N – OH
(ii) A is CH3COOH
B is CH3COCl
(b) (i) Iodoform test
(ii) Tollen’s test
(c) CH – C – CH < CH CH OH < CH COOH3 3 3 2 3
O
OR
(a)
CH3
CHO
CrO Cl2 2
(b) C6H
5COCH
3 < CH
3CHO < HCHO
(c) Due to –I effect of Cl
(d) CH3CH
2CH = CH – CH
2CHO
(e) C H O3 6
I + NaOH2
NaOH + I2
CH CCH3 3
CH CH CHO3 2
O(A)
(B)
CHI3
No ppt.
Yellow
� � �
(21)
Mathematics (Code-A) Solutions of Sample Question Paper for Class XII
SECTION-A
1. a b�
�
= ˆ ˆ ˆ ˆ ˆ ˆ4 2 2i j k i j k
= ˆ ˆ ˆ6 3 2i j k
Unit vector parallel to a b�
�
=
ˆ ˆ ˆ6 3 2
36 9 4
i j k
= ˆ ˆ ˆ6 3 2
7
i j k
2. 1tan 3
= 3
1cot 3
= 6
Hence, 3 6 2
⎛ ⎞ ⎜ ⎟⎝ ⎠
3. A2 = A
7A – (I + A)3
7A –[(I + A)2(I + A)] = 7A – [(II + AA + 2AI) (I + A)]
= 7A – [I + A2 + 2AI] [I + A]
= 7A – [I + A + 2A] [I + A]
= 7A – [I + 3A] [I + A]
= 7A – [I I + IA + 3AI + 3A2]
= 7A – [I + A + 3A + 3A]
= – I
4.
2 2sin cos
sin cos
x xdx
x x
∫
= cos2
2sin2
xdx
x
∫
= 2 cot2xdx ∫
= 2log | sin2 |
2
x+ C
= – log | sin 2x | + C
SECTION-B
5.3 7 8 7
2 4 6 4
x
On expanding both determinants we get
MathematicsMathematicsMathematicsMathematicsMathematics - Class XII (Code-A)
SOLUTIONS
(22)
Solutions of Sample Question Paper for Class XII Mathematics (Code-A)
12x + 14 = 32 – 42
12x + 14 = –10
12x = –24
x = –2
6. R(x) = 3x2 + 36x + 5
MR = dR
dx= 6x + 36
When x = 5
MR = 30 + 36 = 66
7. Let c�
be any vector perpendicular to anda b
��
then ( )c a b �
� �
ˆ ˆ ˆ ˆ ˆ ˆ{( 2 3 ) (3 2 )}c i j k i j k �
1 2 3 11 7
3 1 2
i j k
c i j k
�
Now vector of magnitude 171 in the direction of c�
is given by
= magnitude ˆc
= ( 11 7 )
1711 121 49
i j k
= i – 11j – 7k
8. f(x) =
0
sin
x
t tdt∫
f (x) = 1 x sin x – 0
= x sin x
9. y = x
3
dy
dx
⎛ ⎞⎜ ⎟⎝ ⎠ +
2
2
d y
dx
Order of equation = 2
Degree of equation = 1
Hence sum of order and degree = 3
10. Given A2 = kA
1 1 1 1 1 1
1 1 1 1 1 1k
⎡ ⎤ ⎡ ⎤ ⎡ ⎤⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎣ ⎦ ⎣ ⎦ ⎣ ⎦
2 22
2 2
k kk
k k
⎡ ⎤ ⎡ ⎤ ⇒ ⎢ ⎥ ⎢ ⎥ ⎣ ⎦ ⎣ ⎦
11.2 2
1 1x y dx y x dy = 0
2 2
1 1
x ydx dy
x y
= 0
Integrating we get, 2 2
1 1
x ydx dy
x y
∫ ∫ = 0
2 21 1x y = c
(23)
Mathematics (Code-A) Solutions of Sample Question Paper for Class XII
12. I =
4
2
21
xdx
x ∫
Put x2 + 1 = t
2xdx = dt at x = 2
xdx = 1
2dt t = 5
at x = 4
t = 17
I =
17
5
1/ 2
∫ dtt
= 175
1 1 17log | | log
2 2 5t
SECTION-C
13. Prob. of step forward p = .4
Prob. of step backward q = .6
So by binomial distribution
(p + q)5 = 5C0.p5 + 5C
1.p4.q1 + 5C
2.p3.q2 + 5C
3.p2.q3 + 5C
4.p1.q4 + 5C
5.q5
Prob. for man so that he is one-step away from starting point will be
= 5C2.p3.q2 + 5C
3.p2.q3
= 10.(.4)3.(.6)2 + 10.(.4)2.(.6)3
= 10(.16).(.36)
= (1.6).(.36)
= .576
OR
E1
E2
E1 is the event that on throwing a dice 1 or 2 comes
So 1
2 1( )
6 3P E
E2 is the event that on throwing a dice 3, 4, 5, 6 comes
So 2
4 2( )
6 3P E
If A is event that on throwing coin only one tail is obtained.
Then for Prob. of exactly one tail if he got 3, 4, 5 or 6 is
2E
PA
⎛ ⎞⎜ ⎟⎝ ⎠ =
2
2
1 2
1 2
( )
( ) ( )
AP E P
E
A AP E P P E P
E E
⎛ ⎞ ⎜ ⎟⎝ ⎠
⎛ ⎞ ⎛ ⎞ ⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠
2
AP
E
⎛ ⎞⎜ ⎟⎝ ⎠ =
1,
2
1
AP
E
⎛ ⎞⎜ ⎟⎝ ⎠
= 3
8
(24)
Solutions of Sample Question Paper for Class XII Mathematics (Code-A)
2
AP
E
⎛ ⎞⎜ ⎟⎝ ⎠ =
2 1
3 2
2 1 1 3
3 2 3 8
=
1
3
1 1
3 8
= 1
3×24
11=
8
11
14. We have,
P.V. of A = ˆ ˆ ˆ3 6 9i j k
P.V. of B = ˆ ˆ ˆ2 3i j k
P.V. of C = ˆ ˆ ˆ2 3i j k
P.V. of D = ˆ ˆ ˆ4 6i j k
AB
����
= ˆ ˆ ˆ2 4 6i j k
AC
����
= ˆ ˆ ˆ3 8i j k
AD
����
= ˆ ˆ( 9)i k
Now, AB AC AD ���� ���� ����
2 4 6
1 3 8 0
1 0 ( 9)
–2(–3 + 27) + 4(– + 9 + 8) –6(0 + 3) = 0
6 – 54 – 4 + 68 – 18 = 0
2 – 4 = 0
= 2
, ,AB AC AD
���� ���� ����
are coplanar and so the points A, B, C and D are coplanar.
15. If the given lines are intersecting then the shortest distance between the lines is zero and also they have same
common point ˆ ˆ ˆ ˆ ˆ ˆ3 2 4 ( 2 2 )r i j k i j k �
3
1
x =
2
2
y =
4
2
z =(Let)
Let P is ( + 3, 2 + 2, 2 – 4)
Also, ˆ ˆ ˆ ˆ ˆ5 2 (3 2 6 )r i j i j k �
5
3
x =
2
2
y =
0
6
z =(Let)
Let Q is (3 + 5, 2 – 2, 6)
If lines are intersecting then coordinate of point P and Q will be same
+ 3 = 3 + 5 ..... (1)
2 + 2 = 2 – 2 ..... (2)
2 – 4 = 6 ..... (3)
Solve (2) and (3)
+ 1 = – 1
– 2 = 3 – + –
3 = –2 – 1
4 = –2
2
Put = –2 ..... (3)
2 – 4 = 6(–2)
(25)
Mathematics (Code-A) Solutions of Sample Question Paper for Class XII
2 = –12 + 4
2 = –8
4 Put and in (1)
+ 3 = 3 + 5
–4 + 3 = 3(–2) + 5
–1 = –1
from = –4 then P is (–1, –6, –12)
from = –2 then Q is (–1, –6, –12)
as P and Q are same
Lines are intersecting lines and their point of intersection is (–1, –6, –12)
OR
A(2, 1, –1) ; B(–1, 3, 4)
90°
A B
AB
����
= OB OA���� ����
AB
����
= ˆ ˆ ˆ3 2 5i j k Given plane x – 2y + 4z = 10
1
n
�
= ˆ ˆ ˆ2 4i j k
The required plane is perpendicular to given plane.
n
�
of required plane will be perpendicular to 1
n
�
and AB
����
1
n n AB����� �
�
1n
�
= i – 2j + 4k
AB
����
= ˆ ˆ ˆ3 2 5i j k
1n AB
����
�
= ˆ ˆ ˆ18 17 4i j k
Required plane is
r n� �
= a n� �
ˆ ˆ ˆ( 18 17 4 )r i j k �
= ˆ ˆ ˆ ˆ ˆ ˆ(2 ) ( 18 17 4 )i j k i j k
ˆ ˆ ˆ( 18 17 4 )r i j k �
= –36 – 17 + 4
ˆ ˆ ˆ18 17 4 49r i j k �
18 17 4 49x y z
16. I = 5( 3)
dx
x x ∫
I =
4
5 5( 3)
x dx
x x ∫
(26)
Solutions of Sample Question Paper for Class XII Mathematics (Code-A)
Let x5 = t 5x4dx = dt
I = 1
5 ( 3)
dt
t t ∫
I = 1 1 1 1
5 3 3dt
t t
⎛ ⎞ ⎜ ⎟⎝ ⎠∫
I = 1log log( 3)
15t t c
I = 1log
15 3
tc
t
⎛ ⎞ ⎜ ⎟⎝ ⎠
I =
5
5
1log
15 3
xc
x
⎛ ⎞⎜ ⎟⎝ ⎠
17. Let 11 3
sin2 4
= then
3
4= sin 2
Now, tan11 3
sin2 4
⎛ ⎞⎜ ⎟⎝ ⎠ = tan
If sin 2 = 3
4 then
2
2tan
1 tan
= 3
4
8 tan = 3 + 3tan23 tan2 – 8 tan + 3 = 0
tan = 8 64 4 3 3
6
= 4 7
3
tan11 3
sin2 4
⎛ ⎞⎜ ⎟⎝ ⎠ =
4 7
3
Hence proved.
18.dy
dx= (1 + x) + y(1 + x)
or,dy
dx= (1 + y)(1 + x)
or,1
dy
y = (1 + x) dx
1
dy
y∫ = (1 )x dx∫
log |1 + y| = x +
2
2
x
+ C
Given, y = 0 when x = 1
i.e., log |1 + 0| = 3
2 + c
C = 3
2
(27)
Mathematics (Code-A) Solutions of Sample Question Paper for Class XII
The particular solution is
log |1 + y | =
2
2
x
+ x–3
2
or, the answer can expressed as
log |1 + y | =
22 3
2
x x
or, 2
2 3 /21
x x
y e
or, 2
2 3 /21
x x
y e
19. I =
22
2
0
cos
1 3sin
xdxdx
x
∫
I =
22
2
0
1 sin
1 3sin
xdx
x
∫
I =
2
2
0
1 4 1
3 3 (1 3sin )dx
x
⎡ ⎤ ⎢ ⎥⎣ ⎦∫
I =
2 2
2
0 0
1 4 1
3 3 1 3sindx dx
x
∫ ∫
I =
22
2
0
1 4 sec
3 2 3 1 4tan
xdx
x
∫
Let 2 tan x = t
sec2x dx = 1
2dt
I = 2
0
4 1
6 3 2 1
dt
t
∫
I = 1
0
2tan
6 3t
I = 2
6 3 2
I = 6 3
I = 6
20. y = sin–1
12 3
1 (36)
x x
x
⎡ ⎤⎢ ⎥⎣ ⎦
y = sin–12 2 3
1 (36)
x x
x
⎡ ⎤ ⎢ ⎥⎣ ⎦
y = sin–1 2
2 (6)
1 (6)
x
x
⎡ ⎤⎢ ⎥⎣ ⎦
(28)
Solutions of Sample Question Paper for Class XII Mathematics (Code-A)
y = 2 tan–1(6)x
dy
dx= 2
26 log6
1 (6)
x
x
dy
dx =
2 6 log6
1 (36)
x
x
21.
1 1, if 1 0
( )2 1
, if 0 11
kx kxx
xf x
xx
x
⎧ ⎪⎪ ⎨⎪
⎪⎩ function f(x) is continuous at x = 0
f(0) = 0
lim ( )x
f x
0 1
0 1
= 0
1 1limx
kx kx
x
⎛ ⎞ ⎜ ⎟⎝ ⎠
–1 = 0
1 1 1 1lim
1 1x
kx kx kx kx
x kx kx
⎛ ⎞ ⎛ ⎞ ⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠
–1 =
0
1 1lim
1 1x
kx kx
x kx kx
–1 = 0
2lim
1 1x
k
kx kx
–1 = 2
2
k k = –1
OR
x = a cos3 and y = a sin3
dx
d = –3a cos2sin and
dy
d = 3a sin2 cos
dy
dx =
dy
d
dx
d
dy
dx = –tan
2
2
d y
dx= –sec2
d
dx
2
2
d y
dx =
2
2
1sec
3 cos sina
2
2
d y
dx =
41sec cosec
3a
2
2
6
d y
dx
⎛ ⎞⎜ ⎟⎝ ⎠
=
4
1 22
3 3a
⎛ ⎞ ⎜ ⎟⎝ ⎠=
32
27a
(29)
Mathematics (Code-A) Solutions of Sample Question Paper for Class XII
22. We have,
dy
dx=
1
2
tan
1
x y
x
21
dy y
dx x
=
1
2
tan
1
x
x
I.F = 2
1
1dx
xe
∫ = 1
tan x
e
1tan
.
x
y e
= 1
1
tan
2
tan
1
xx
e dxx
∫
Put t = tan–1x
dt = 2
1
1
dx
x
=
I I I
tt e dt∫
= 1t t
t e e dt ∫1
tan x
y e
= t et – et + c
1tan x
y e
= (tan–1 x – 1) 1
tan x
e c
y = tan–1 x – 1 + 1
tan x
c e
23. f : R+ [4, )
f(x) = x2 + 4
f(x) = 2x > 0 (one - one)
As, f(x) = x2 + 4 4
Range = [4, ) = co-domain
onto
So f is invertible.
Further : y = x2 + 4
y – 4 = x2 x = ± 4y
As x > 0 so x = 4y
y = 4x = f –1(x)
Or, f–1(y) = 4y
SECTION-D
24. If zmax
= 100x + 120y
Type A Type B
Worker
Capital
2
3
3
1
30
17
Subject to,
(30)
Solutions of Sample Question Paper for Class XII Mathematics (Code-A)
2x + 3y 30
3x + y 17
x 0
y 0
Let object of type A = x
Object of type B = y
y
D(0, 17)
(0, 10) C E (3, 8)
A(0, 0) (15, 0)
B
(2 + 3 30)x y (3 + ) 17x y
n
Coordinate
O
E
C
A
(0, 0)
(3, 8)
(0, 10)
pts. z = 100 + 120max
x y
z = 0
z = 300 + 960 = 1260
z = 1200
173
,0 z =1700
3
maximum revenue = 1260
25.
2
2
2
( )
( )
( )
x y zx zy
zx z y xy
zy xy z x
R1 zR
1, R
2 xR
2, R
3 yR
3
We get
2 2 2
2 2 2
2 2 2
( ) 1
( )
( )
z x y z x z y
zx x z y x y
xyz
zy xy y z x
Taking z, x, y common from C1, C
2, C
3
respectively, we get
2 2 2
2 2 2
2 2 2
( )
( )
( )
x y z z
xyzx z y x
xyz
y y z x
C1 C
1 – C
3, C
2 C
2 – C
3
(31)
Mathematics (Code-A) Solutions of Sample Question Paper for Class XII
2 2 2
2 2 2
2 2 2 2 2
( ) 0
0 ( )
( ) ( ) ( )
x y z z
z y x x
y z x y z x z x
2
2
2
( )( ) 0
0 ( )( )
( )( ) ( )( ) ( )
x y z x y z z
z y x z y x x
y z x y z x y z x y z x z x
2
2 2
2
0
( ) 0
( )
x y z z
x y z z y x x
y z x y z x z x
R
3 R
3 – R
2 – R
1
2
2 2
0
0
2 2 2
x y z z
x y z z y x x
x z zx
1 1 3 2 2 3
1 1,C C C C C C
z x
2
2
22 2
0 0 2
zx y z
x
xx y z z y x
z
zx
Expanding along R3
2xz(x + y + z)2 2 2
x zx y z y
z x
⎛ ⎞ ⎜ ⎟⎝ ⎠
2xz(x + y + z)2 (xz + xy + yz + y2 – xz)
2xyz(x + y + z)3 = RHS
26. P1 is ˆ ˆ3 6 0r i j
�
P1 is x + 3y – 6 = 0
P2 is ˆ ˆ ˆ3 4r i j k
�
P2 is 3x – y – 4z = 0
Equation of plane passing through intersection of P1 and P
2 is P
1 + P
2 = 0
(x + 3y – 6) + (3x – y – 4z) = 0
(1 + 3)x + (3 – )y + (–4)z + (–6) = 0
Its distance from (0, 0, 0) is 1.
2 2 2
0 0 0 61
1 3 3 4
36 = (1 + 3)2 + (3 – )2 + (–4)2
36 = 1 + 92 + 6 + 9 + 2 – 6 + 162
36 = 262 + 10 262 = 26 = ± 1
Hence required plane is
For = 1, (x + 3y – 6) + 1(3x – y – 4z) = 0
(32)
Solutions of Sample Question Paper for Class XII Mathematics (Code-A)
4x + 2y – 4z – 6 = 0
For = –1, (x + 3y – 6) – 1(3x – y – 4z) = 0
–2x + 4y + 4z – 6 = 0
OR
P1 is ˆ ˆ ˆ2r i j k
�
= 5
1
n
�
= ˆ ˆ ˆ2i j k
P2 is ˆ ˆ ˆ3r i j k
�
= 6
2n
�
= ˆ ˆ ˆ3i j k
The line parallel to plane P1 and P
2 will be perpendicular to
1 2and .n n
� �
1 2||b n n
�� �
1n
�
= ˆ ˆ ˆ2i j k
2n
�
= ˆ ˆ ˆ3i j k
1 2n n� �
= ˆ ˆ ˆ3 5 4i j k
b�
= ˆ ˆ ˆ3 5 4i j k Point is (1, 2, 3).
a
�
= ˆ ˆ ˆ2 3i j k
required line is r a b �
� �
ˆ ˆ ˆ ˆ ˆ ˆ2 3 3 5 4r i j k i j k �
27. 5 Red2 Black
(i) = 0, 1, 2(ii) yes, is a random variable it varies from 0 to 2
x
x
urn.
No. of blackballs = x
P x( )
0 1 2
2042 20
42 2
42
(a) P(0) = P(R1) × P
2
1
R
R
⎛ ⎞⎜ ⎟⎝ ⎠ =
5 4
7 6 =
20
42
(b) P(1) = P(R1) × P
2 2
1
1 1
( )B R
P B PR B
⎛ ⎞ ⎛ ⎞ ⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠
= 5 2 2 5
7 6 7 6 =
20
42
(c) P(2) = P(B1) ×
2
1
BP
B
⎛ ⎞⎜ ⎟⎝ ⎠ =
2 1
7 6 =
2
42
(iii) Mean ( )x = x1P
1 + x
2P
2 + x
3P
3
(33)
Mathematics (Code-A) Solutions of Sample Question Paper for Class XII
= 20 20 2
0 1 242 42 42
⎛ ⎞ ⎛ ⎞ ⎛ ⎞ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠ ⎝ ⎠
= 24
42=4
7
(iv) Variance =
22
0
( )x
P x x x
∑ =
2
4(0) 0
7P
⎛ ⎞ ⎜ ⎟⎝ ⎠
2 2
4 4(1) 1 (2) 2
7 7P P
⎛ ⎞ ⎛ ⎞ ⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠
= 20 16 20 9 2 100
42 49 42 49 42 49
= 50
147
28. f(x) = 4 3 4,
3 4 3
xx R
x
f is one-one :
Let 1 2
4,
3x x R and f(x
1) = f(x
2)
1
1
4 3
3 4
x
x
=
2
2
4 3
3 4
x
x
12x1x
2 + 16x
1 + 9x
2 + 12 = 12x
1x
2 + 9x
1 + 16x
2 + 12
7x1 = 7x
2 x
1 = x
2
f is one-one.
f is onto :
Let 43
k R be any number
f(x) = k 4 3
3 4
xk
x
4x + 3 = 3kx + 4k
x = 4 3
4 3
k
k
Also,4 3
4 3
k
k
=4
3
implies –9 = –16 (which is impossible)
4 3
4 3
kf k
k
⎛ ⎞ ⎜ ⎟⎝ ⎠ i.e., f is onto
The function f is invertible i.e., f–1 exist inverse of f.
Let f–1(x) = k
f(k) = x
4 3
3 4
k
k
= x
f–1(x) = 4 3 4,
4 3 3
xx R
x
f–1(0) = –3
4
(34)
Solutions of Sample Question Paper for Class XII Mathematics (Code-A)
and when
f–1(x) = 2
4 3
4 3
x
x
= 2
4x – 3 = 8 – 6x
10x = 11
x = 11
10
OR
(i) Let (e, f) be the identity element for *
for (a, b) Q × Q, we have
(a, b) * (e, f) = (a, b) = (e, f) * (a, b)
(ae, af + b) = (a, b) = (ea, eb + f)
ae = a, af + b = b, a = ea b = eb + f
e = 1, af = 0, e = 1, b = (I)b + f (∵ a need not be '0')
e = 1, f = 0, e = 1, f = 0
(e, f) = (1, 0) Q × Q
(1, 0) is the identity element of A
(ii) Let (a, b) Q × Q
Let (c, d) Q × Q
such that
(a, b) * (c, d) = (1, 0) = (c, d) * (a, b)
(ac, ad + b) = (1, 0) = (ca, cb + d)
ac = 1, ad + b = 0, ca = 1, cb + d = 0
c = 1
a, d =
ba
, 1
a
⎛ ⎞⎜ ⎟⎝ ⎠ b + d = 0 (a 0)
(c, d) = 1,
b
a a
⎛ ⎞⎜ ⎟⎝ ⎠ (a 0)
for a 0 (a, b)–1 = 1,
b
a a
⎛ ⎞⎜ ⎟⎝ ⎠
29. Let A = (–1, 2)
B = (1, 5)
C = (3, 4)
B(1, 5)
C(3, 4)A( 1, 2)
L M N
We have to find the area of ABC.
(35)
Mathematics (Code-A) Solutions of Sample Question Paper for Class XII
Find equation of line AB y – 5 = 2 5
( 1)1 1
x⎛ ⎞ ⎜ ⎟⎝ ⎠
y – 5 = 31
2x
2y – 10 = 3x – 3
3x – 2y + 7 = 0 ..... (1)
y = 3 7
2
x
Equation of BC y – 4 = 5 43
1 3x
⎛ ⎞ ⎜ ⎟⎝ ⎠
y – 4 = 13
2x
x + 2y – 11 = 0 ..... (2)
y = 11
2
x
Equation of AC :
y – 4 = 2 43
1 3x
⎛ ⎞ ⎜ ⎟⎝ ⎠
y – 4 = 13 2 8 3
2x y x ⇒
x – 2y + 5 = 0 ..... (3)
y = 5
2
x
So, required area =
1 3 3
1 1 1
3 7 11 5
2 2 2
x x xdx dx dx
⎛ ⎞ ⎛ ⎞ ⎛ ⎞ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠ ⎝ ⎠∫ ∫ ∫
=
1 3 32 2 2
1 1 1
1 3 1 17 11 5
2 2 2 2 2 2
x x xx x x
⎡ ⎤ ⎡ ⎤ ⎡ ⎤ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎣ ⎦ ⎣ ⎦ ⎣ ⎦
= 1 3 3 1 9 1 1 9 1
7 7 33 11 15 52 2 2 2 2 2 2 2 2
⎡ ⎤ ⎡ ⎤ ⎡ ⎤⎛ ⎞ ⎛ ⎞ ⎛ ⎞ ⎛ ⎞ ⎛ ⎞ ⎛ ⎞ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠⎣ ⎦ ⎣ ⎦ ⎣ ⎦
= 114 22 4 24
2 = 1
36 28 42
square unit
� � �
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